Method for controlling fires

ABSTRACT

A method or system for controlling fires is provided particularly for use in areas where food is prepared using fats and greases. The method or system provides for detecting flame or excessive heat, the presence of which automatically releases a high volume flow of extinguishant over at least one of several critical areas of the fire so as to rapidly eliminate any flame and rapidly reduce the temperature in the critical areas. The method or system then provides for automatically reducing the rate of flow of the extinguishant from the same source of extinguishant and continues to flow the extinguishant at said reduced rate for a considerable period of time sufficient to reduce the temperature of the area below the flame auto-ignition point.

169*47'. "OR 395849688 5R [72] inventors Donald Lee Duncan Oak Lawn;George A. Utesch, Jr., Chicago, both of, Ill. [211 App]. No. 847,162[22] Filed Aug. 4, 1969 [45] Patented June 15, 1971 [73] AssigneeGeneral Fire Extinguisher Corporation [54] METHOD FOR CONTROLLING FIRES7 Claims, 9 Drawing Figs.

[52] 1.1.8. (I 169/2, 169/ 19 [51] Int. Cl A62c 3/00 [50] Field otSearch169/1,2,5, 9, l 1, 19, 26, 20

[56] References Cited UNITED STATES PATENTS 1,881,709 10/1932 Laswell169/11 2,732,017 1/1956 Fleming..... 169/2 X 2,742,094 4/1956Mathisen... 169/9 X 3,012,613 12/1961 Diquattro 169/9 PrimaryExaminer-M. Henson Wood, Jr. Assistant Examiner- Edwin D. GrantAttarneyHofgren, Wegren, Allen, Stellman & McCord ABSTRACT: A method orsystem for controlling fires is provided particularly for use in areaswhere food is prepared using fats and greases. The method or systemprovides for detecting flame or excessive heat, the presence of whichautomatically releases a high volume flow of extinguishant over at leastone of several critical areas of the fire so as to rapidly eliminate anyflame and rapidly reduce the temperature in the critical areas. Themethod or system then provides for automatically reducing the rate offlow of the extinguishant from the same source of extinguishant andcontinues to flow the extinguishant at said reduced rate for aconsiderable period of time sufficient to reduce the temperature of thearea below the flame auto-ignition point.

PATENTED JUN 1 519?:

SHEET 3 OF 3 METHOD FOR CONTROLLING FIRES BACKGROUND OF THE INVENTION IField of the Invention This invention relates to a method or system forcontrolling fires and more particularly to a method or system forcontrolling fires in areasgwhere food is prepared by the use of fats orgrease. v

2. Description of the Prior Art In fire control, one of the hardestfires to put out and to keep out is a fire that develops in and aroundareas where considerable amounts of fat or grease are used in foodpreparation. This is particularly true in the equipment known as deepfryers" where potatoes, fish and other foodstuffs are immersed in a vatof fat or grease which is generally maintained at temperatures around300 to 400 Fahrenheit.

Temperature controls are provided so that if the temperature of thematerial in the vat exceeds a predetermined amount, the heat source forthe vat is shut off. Occasionally, the controls fail and the temperaturecontinues to rise until the auto-ignition point is reached.

Another source of fire around a cooking area is created by theaccumulation of grease and fat in the hood or exhaust duct area abovethe appliance where, when sufficient grease or fat has accumulated andthe temperature rises above the auto-ignition point, a fire can developfrom burning the fats or greases.

It has generally not been too difficult to put out the flame of either avat fire or a hood and exhaust duct fire, but it has been difficult tokeep the fire out because the flame will raise the temperature to around800 F. so that, even though the flame is momentarily extinguished, thegrease will immediately reignite as long as the temperature is above theauto-ignition point.

In current use there are two systems operating on different principlesfor controlling the reignition of the flames. The first is to blanketthe grease and fat area with powder to smother the flame and preventreignition. The second approach is to cool the grease and fat of thesurrounding area by an agent that has a cooling effect.

Of the two alternative systems on the market today, the first system,wherein powder is mixed with a propellant such as CO and is spread as ablanket over the affected area, has the principal disadvantage that theequipment has to be carefully watched until it cools down below theauto-ignition point and then has to be completely cleaned before it canbe reused. This means discarding large amounts of usable fats and/orgrease and the like.

The second currently used system employs two cylinders of carbon dioxide(CO separately piped to the cooking area, wherein the first cylinderapplies the CO, at a fast rate to extinguish the flame and then thesecond cylinder is activated to propel CO, at a slow rate over thegrease to cool the grease below the autoignition point. Carbon dioxideby its nature requires large volumes of material in order to effectivelycontrol the more common fires in deep fry units and the like.

SUMMARY OF THE INVENTION In our invention, we provide an improved methodor system of fire control using a single container of extinguishant anda valve arrangement which makes it possible to control the flame andcool the area effectively by a unique combination of steps. The stepsbroadly include detecting the presence of excessive heat or a flame,automatically operating a valve for releasing a large volume ofextinguishant into at least one of several areas for rapidlyextinguishing any flame that may be present. The method or system thenprovides for automatically reducing the rate of flow of extinguishantfrom the cylinder and continuing to flow the extinguishant at thereduced rate over the affected area for a considerable period of time,thereby cooling the area well below the autoignition point.

2 DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a deep-frypiece of equipment with a schematic showing the location of the improvedfire control apparatus thereon;

FIGS. 2 and 3 are top plan views of two positions of a cam releasemechanism of the invention;

FIG. 4 is a cross-sectional view taken along a plane passing verticallythrough the valve, showing the valve in cocked position;

FIG. 5 is a cross-sectional view similar to FIG. 4 showing the valve inthe initial operating position;

FIG. 6 is a cross-sectional schematic view taken along a vertical planeof FIG. I showing the relationship of various elements of the firecontrol apparatus;

FIG. 7 is an enlarged cross-sectional view of one of the improved firecontrol nozzle arrangements;

FIG. 8 is an enlarged cross-sectional view showing the puncturing memberof the valve in the cocked position, and

FIG. 9 is an enlarged cross-sectional view similar to FIG. 8, onlyshowing the valve puncturing member in puncturing position. Referringnow to the drawings, there is shown in FIG. 1 and 6 a tire controlapparatus 10 of the instant invention as applied to a piece ofcommercial deep-fry equipment 12 of the type in common use inrestaurants offering fried foods, such as French fried potatoes, friedshrimp, fried fish and the like. It is intended that the tire controlapparatus, method or system could be applied to other pieces ofequipment where an initial high volume, short duration blast ofextinguishant is required followed immediately by a lower volume butconsiderably longer duration flow of extinguishant, first to extinguishthe flame and then to lower the temperature of burnable materials andthe surrounding equipment.

The illustrated deep-fry equipment 12 is composed of a stainless steelor porcelain body 14 having legs 15 and casters 16 upon which theequipment can be moved if desired. Doors 17 are provided on the front ofthe body 14 for storage of cooking implements (not shown). A ventportion 19 extends upwardly from the rear of the body 14 and has a hood18 projecting forwardly in overhanging but vertically spacedrelationship to a pair of open vats 20 formed in the body I4. A stack orexhaust duct 21 communicates with the inside of the hood l8 and isconnected to an exhaust system for the restaurant. The hood 18 isprovided with removable screens or filters 22 which are intended tofilter the fumes and vapors and to collect droplets of fat or greasethat are carried upward from the hot fat or grease in the vats 20 as iswell known in the food preparation art.

As best shown in FIG.- 6, the vats 20 have ducts 24 passing through thelower portion thereof in which an appropriate heat source 25 ispositioned to supply heat to the vats 20 for maintaining the fat orgrease in the vat at a predetermined cooking temperature. In theillustrated form, the heat source 25 is a flame fed by a gas sourcethrough pipes 26 with the exhaust gases and products of combustion goingthrough the ducts 24, vent portion 19 into the hood l8 and up the stack21. The source of heat could be an electric unit or any other compatiblesystem. An appropriate set of controls and thermostats are provided inthe vat 20 and in the piping 26 whereby the desired temperature of thefat or grease can be set and automatically maintained. In normal use ofthe equipment, the vat 20 is filled to the correct level with fat orgrease and by means of the heat source 25 it is heated to the desiredtemperature. The potatoes or other food to be deep fried are placed in abasket 28 which is suspended in the hot fat or grease by means ofappropriate suspension means 30. The vapors and odors from the cookingare drawn up through the filter 22 and on up the stack, by action of anexhaust fan.

Occasionally, due to a faulty heat control or thermostat or due toimproper or poor maintenance of the equipment or due to inexperiencedoperating personnel, the cooking temperatures become elevated to a pointthat flames will auto-ignite either from the vat, in the hood or in thestack. The flame will immediately raise the temperature of the fat orgrease in the vat, hood and stack to a point that even though the flameis momentarily extinguished, it will immediately reauto-ignite intoflame again. Therefore, to effectively bring the fire under control notonly must the flame be extinguished but also the surrounding area mustbe cooled to below the auto-ignition point of the fats or greases. Theinvention is directed to a novel valve and nozzle in a fire controlapparatus whereby the flame is extinguished and the temperature of theaffected area is reduced to prevent reauto-ignition of the flame.

As shown schematically in FIGS. 1 and 6, the fire control apparatus iscomprised of a cylinder 35 containing an appropriate extinguishant underpressure. The cylinder 35 is held in a bracket on the sides or back ofthe body 14 or can be nested in a frame on the top of the hood 18. Theexact location is primarily a matter of servicing convenience. The onlyrequirement is that it be fixed relative to the stack or exhaust duct21. The fire extinguisher head assembly 36 is removably connected to thecylinder 35, as will be described hereinafter, and has a release cam 38pivotally mounted thereon which is connected by a cable 39 to a fusiblelink 40 resiliently positioned in the stack or exhaust duct 21 by aspring 41. Flame or excessive heat in the stack or exhaust duct 21 willmelt the link 40 releasing the cable 39 and release cam 38 to actuatethe fire extinguisher and head assembly 36 as will be described indetail hereinafter.

The head assembly 36 has an outlet 42 in the wall of the discharge valvebody 44 through which outlet 42 extinguishant will flow. Appropriatepiping 45 connects outlet 42 with a nozzle 46 in the stack or exhaustduct 21. The piping 45 has a branch 48 which connects in one portionthrough body 14 to a nozzle 49 in the hood 18 above filters 22 thereinand in another portion to a pair of nozzles 50 projecting into the areaabove the fat or grease in the vats 20. A cable 51 is connected to aspring 52 which in turn is connected to the release cam 38 for pivotingthe cam 38 in a clockwise direction about a pivot 53. The spring 52 isnot as strong as spring 41 so that spring 41 overcomes the loading ofspring 52. The cable 51 and spring 52 are used to release the cam 38when the frangible link 40 disintegrates due to a fire in the equipment.

The head assembly 36 as shown in FIGS. 4 and has the discharge valvebody 44 bored or recessed at 54, which bore extends from one end thereofthroughout a major portion of the length of the body and terminates in ashoulder 55 through which shoulder an aperture 56 extends axially theremaining length of the body. The mouth of the recess 54 is internallythreaded at 58 into which is screwed a valve cap 59 which is aperturedat 60 in axial alignment with aperture 56 in the body 44. The pivot pin53 for the release cam 38 is seated in the external end face of the cap59 about which pin the release cam 38 pivots. The cam 38 has anarcuatelyshaped keyhole slot 62 therethrough (FIGS. 2, 3) with the centers 63, 64respectively, of the large diameter end portion 65 and the smalldiameter end portion 66 lying on the same circle, which circle iscentered at the center of the pivot pin 53. The circle through thecenters 63, 64 of the keyhole slot 62 also passes through the center ofthe aperture 60 in the valve cap 59.

An elongate valve stem 70 is slidably mounted in the aligned apertures60 and 56 in the cap 59 and valve body 44, respectively, with one endportion 71 extending upwardly beyond the cap 59 and in which portion 71is formed a pair of axially spaced annular grooves or recesses 72, 73.An O-ring 74 is seated in recess 73 for sealing the stem 70 with the cap59. Within the valve body 44 and surrounding the valve stem 70 is acompression spring 75 which is retained between the valve cap 59 and avalve retaining collar 76 by means of collar drive pin 77 passingthrough the collar 76 and the valve stem 70. The cap 59 has a springcentering member 79 fixed on the inner surface thereof such that thespring 75 will be centered with respect to the valve stem 70 by thecombined action of said member 79 and the stepped down shelf 80 on theretaining collar 76.

The lower end portion 81 of the valve stem 70 is hollowed or tapped asat 82 with the end severed at an angle and dressed to form a puncturingpoint 83. At appropriate locations along the length of said end portion81 is formed at least two pairs of axially spaced apart outlet openings85, 86. Each pair of openings will preferably consist of one opening inone side and another opening diametrically opposite thereto butvariations therefrom have been found to work successfully. in the wallof the opening 56 of the valve body 44 is an annular recess 88 in whichis seated an O-ring 89 which is adapted to provide a seal between thevalve stem and the valve body 44. The recess 88 and O-ring 89 arelocated between the outlet 42 of the valve body 44 and the recess 54 inwhich the spring is located to prevent extinguishant from leaking intosaid cavity 54 and to prevent loss of pressure in the system.

The valve stem 70 with the spring 75 trapped between the valve cap 59and the retaining collar 76 is assembled with the valve body 44 bythreading the end portion 81 with the puncture point 83 through theopening 56 so that the threaded cap 59 can be drawn down tight in thevalve body. An orifice shut off bushing 90 has an aperture 92 throughthe center thereof which aperture has a recess forming a shoulder 93 atthe inner end thereof on which shoulder 93 an O-ring or gasket 95 isnested. The bushing 90 is inserted in the threaded lower end of thevalve body 44 with the puncture point 83 on the lower end portion 81 ofthe valve stem passing into the aperture 92. The O-ring or gasket 95sealingly engages the outer surface of the valve stem 70 as the bushingis threaded into nested relation in the valve body. With the bushing 90drawn up tight the gasket 95 will form a pressure seal between the valvebody and the valve stem.

Trapped between a flange 96 on the bushing 90 and the walls of a recess97 formed in the one edge of valve body 44 is the discharge valveretaining collar 99. The fit between the collar 99 and the valve body 44will permit the collar to turn relative to the valve body. The collar 99has an opening through its center for accommodating passage of the valvebody 44 and is internally threaded in its cylindrical portion forattachment to the refillable cylinder or tank 35 of extinguishant.

Carried on the cylinder or tank 35 is a storage cylinder valve head 100which is axially bored at 102. A bore 103 is disposed parallel to theaxial bore 102 and intersects with a bore 104 in a threaded hub 105projecting from the sidewall of said head 100. A standard pressure gauge107 with a threaded stub 108 is threaded into the bore of hub 105 sothat when the threaded nipple 110 on the valve head 100 is screwed intothe cylinder or tank 35, the pressure in the cylinder will be recordedon the gauge 107. The valve head 100 has a syphon tube 112 connected inthe nipple 110 and projects down into the interior of the cylinder ortank 35 in the usual manner for the most efficient method of dischargingthe extinguishant from the cylinder.

An oversized bore 114 is concentrically formed with respect to the bore102 in the valve head 100. The bore 114 is threaded and has a valve seat115 formed in the base of the bore around the edge of the bore 102. Arupture disc housing 117 has an opening 118 through the center thereofand is threaded on its outer surface. The one end portion of the opening118 in the housing 117 is enlarged as at 120 for receiving a pair ofwashers 121, 123 between which is sandwiched a rupture disc 124. Withthe washers and disc 124 seated therein, the housing 117 is threadedinto the bore 114 in the valve head 100 so that the washer 123 seats onthe valve seat 115 for pressure sealing the rupture disc housing 117 tothe valve head 100.

In the system, the cylinder or tank 35 is to be filled and sealed withthe just described valve head 100 and rupture disc 124. The top wall ofthe valve head 100 has a circular recess 125 formed therein in which anO-ring or gasket 126 is nested which serves as a seal between the valvehead 100 and the head assembly 36 when the two are assembled.

With a fire control system installed on a deep fry piece of equipment,the valve head assembly 36 is held firmly in a housing or bracket eitheron the piece of equipment to be fire protected or close to it. The valvehead assembly 36 which includes principally thevalve body 44, valve stem70, spring 75, collar 76, cap 59 and release cam 38 is cocked or loadedby manually or mechanically pulling the valve stem 70 upwardout of thecap 59 until the recess 72 is aligned with the release cam 38 whereuponthe release cam 38 is pivoted until the edges of the small diameter endportion 66 of the keyhole slot 62 nest in the recess 72. Release of thevalve stem 70 will permit the coiled spring 75 to urge the top wall ofthe recess 72 against the release cam 38 to hold the valve system in thecocked position. The cable 39 extends from the release cam 38 throughone wall of the stack or exhaust duct 21 and is connected to one side ofthe frangible link 40. The other side of the frangible link 40 isconnected through the wall of the stack 21 to a spring 41 which isanchored to a fixed member. The cable 39 is resiliently connected to therelease cam 38. The cam release spring 52 is connected at one end to afixed point through the cable 51 and is stretched and connected at itsother end to the release cam 38. The cable 39, frangible link 40 andspring 41 are loaded sufficiently to hold the release cam 38 against thetension of spring 52, with the wall 66 of the slot in the cam 38 nestingin the recess 72 in the valve stem 70 as shown in FIG. 2 which is thecocked position of the mechanism shown in FIG. 4. The spring 52 isloaded and attempts to pull the release cam 38 in a clockwise directionto the position of FIG. 3 against therhigher loading of spring41 incable 39. A hand release 130 is connected to the cable 51 and hangs in aposition where it can be quickly grabbed and pulled to overcomethe'tension of the spring 41 to pivot the release cam 38, therebyreleasing the valve stem 70 and actuating the system.

The valve head assembly 36 is connected to a charged cylinder 35 bythreading the collar 99 of the assembly 36 onto the storage cylindervalve head 100. The gasket 126 is compressed between the head assembly36 and the storage valve head 100 to effect a pressure sealtherebetween.

It will be noted that the puncture point of the valve stem 70 is spacedfrom the rupture disc 124 as shown in FIG. 5.

The piping 45 from the outlet 42 of the valve head assembly 36 connectedthrough piping 48 to the nozzles 46, 49 and 50. As illustrated in FlG.7, the nozzle 50-which can be the same as nozzles 46 and 49-is of anovel design and includes a nipple 140 which is blind bored as at 141with branch bores 142 radiating at right angles outwardly therefrom. Adeflector hood or cup 143 is trapped between the enlarged integral nut144 and a snap ring 146 seated in a groove 147 in said nipple 140. Thedeflector hood 143 has cylinder sidewall 149 spaced outwardly and inoverlapping relationship with respect to the bores 142. Theextinguishant from the cylinder is propelled from the bores 142, strikesthe wall 149 of the hood 143 and is deflected horizontally in ascrambled random pattern as, a blanket onto the fat or grease in the vat20. It is important ,to get the extinguishant out of the nozzle fast butnot so fast as to create excessive turbulence which can spread the flameto other surrounding areas. The hood 143 lays the extinguishant down asa blanket over the fire to extinguish the flame and cool the area. Whenthe nozzle 50 is used in the hood or stack, the extinguishant flows overand around the inside of the hood 18 and screen 22 and into the stack orexhaust port 21. The nozzle 50 causes the extinguishant to engulf theaffected areas so as to extinguish the flames and cool the equipment.The nozzle 50 is shown located on the front of the vat nearest thestation occupied by an attendant so that the blast of extinguishanttakes the flame away from the station as it extinguishes the flames andcools the equipment.

In operatiomwhen a flame auto-ignites from thedeep fry equipment, itwill immediately ignite any grease condensed in the hood or stack,rapidly raising the temperature of all affected areas. The frangiblelink 40 in the stack will-disintegrate, releasing the cable 39 whereuponthe spring 52 pivots the release cam 38 disengaging the small end 66 ofthe keyhole slot 62 from the recess 72 in the valve stem. The compressedspring 75 will drive the valve stem 70 through the enlarged end 65 ofthe keyhole slot 62 and puncture the rupture disc .124 with the piercingpoint 83. The pressure of the extinguishant in the cylinder or tank 35will force the extinguishant up the bore 102, into the end of the hollowportion 81 of the valve stem 70 and drive the valve stem back up throughthe valve body 44 to recompress the spring 75. The extinguishant willrapidly flow through both pairs of openings 85, 86 and out the orifice42 through the piping 45 to the nozzles 46, 49 and 50. After a shortperiod of time of high volume flow of extinguishant, the pressure in thecylinder or tank 35 will drop a sufficient amount that the pressure ofthe spring 75 will overcome the pressure in the tank and the valve stem70 will'be forced down byvthe spring 75 until the ports or openings passbelow the O-ringor gasket which will shut off the flow of extinguishantfrom said ports 85. The result of shutting off ports 85 will be to cutin half the flow rate of extinguishant which when coupled with thereduction in pressure in the cylinder 35 will reduce the flow ofextinguishant from the orifice 42 to about one-half of the original flowrate. At the reduced rate of discharge the extinguishant will continueto flow for a considerable period of time until the cylinder 35 isexhausted.

The purpose of the high volume, short durationlow volume, long durationsequence of discharge of extinguishant is to make it possible toproperly control fires of the type described hereinbefore. That is, theinitial high volume blast of. extinguishant flooding the vat, the hoodarea andthe stack quickly puts out the flame. However, if at that pointthe extinguishant ceased flowing, the flame would reignite since thetemperatures of the fat, grease and surrounding surfaces are usuallywell above the auto-ignition point. By automatically changing the flowrate to a substantially reduced amount of continuing at that reducedrate, the extinguishant acts as a coolant and lowers the temperature ofthe fat, grease and surrounding area so that after the passage of apredetermined period of lower volume discharge the possibility offurther auto-ignition is eliminated.

The deep fry equipment can be cleaned up, a new frangible.

link 40 installed, the valve head assembly 36 recocked and a newcylinder 35 assembled thereto ready for an immediate return of theequipment to service.

A specific operative system that has been successfullyused will now bedescribed. ,That is, a fire control system for protection of a specificpiece of deep frying cooking equipment utilized a cylinder 35 holdingapproximately 20 pounds of Freon 1301 (a commercially availableextinguishant) pressurized with nitrogen. The pairs of ports 85 and 86in the valve stem 70 were designed to emit a part of the Freon 1301 inan initial blast. This initial blast was a high volume, short durationblast of extinguishant sufficient to extinguish the flames of a fire.

The valve automatically cuts one pair of ports 85 out of the system andcontinues to discharge the extinguishant at a substantially reduced ratewhereby the remaining Freon 1301 is discharged over an extended periodof time until the cylinder is exhausted. This slower but continuous flowof extinguishant cools the equipment to below the auto-ignition point.

Typical deep fry equipment cooks at between 300 F. and 400 F. Failure ofa control will permit the temperature to go up until at around 640 F.the fat or grease can auto-ignite into flame. The flames generatetemperatures of around 800 F. such that when the-initial blast ofextinguishant floods the area, the flame is extinguished, but thesurrounding temperatures can still be well above the auto-ignitiontemperature. The reduced flow rate over the longer period of time coolsthe surrounding area to a safe temperature well below the auto-ignitiontemperature.

The manner that Freon l30l operates to extinguish a flame and to coolburning material is within the skill of a person in the art and .willnot be. repeated here. Any other extinguishant having similar physicalcharacteristics such as density, cooling capacity, heat absorption andthe like is usable in the system.

By effectively controlling the fire before the temperatures reach orexceed 900 F., no decomposition takes place andsince the Freon 1301 isnontoxic, it will not taint the cooking equipment. Accordingly, after afire the equipment can be returned to service without extensive cleaningand reconditioning being required.

We claim:

l. A method for controlling fires, comprising the steps of rupturing afrangible element by exposure to excessive heat, releasing a highpressure and high volume flow of extinguishant from a storage containerinto a system of fire control piping, directing the high pressure andhigh volume flow of extinguishment over the burning area, automaticallyreducing the pressure and volume of flow of extinguishment from the samesource of extinguishment and over the same area, whereby the largevolume flow will extinguish any flame and the reduced flow will cool thearea below the rekindling point.

2. The method for controlling fires as claimed in claim 1 and whereinthe high volume and high pressure flow of extinguishment is maintainedfor a relatively short period of time and the reduced volume flow ismaintained for a comparatively long period of time.

3. The method for controlling fires as claimed in claim 1 wherein theratio of the duration of the reduced volume flow to the large volumeflow is of the order of 18 to l.

4. A method for controlling grease fires, comprising the steps ofinitially directing a large volume flow of extinguishment over theburning area, continuing said large volume stream of extinguishment fora short period of time, automatically reducing the volume of the flow ofextinguishment from the same source of extinguishment and over the samearea, continuing the reduced volume of flow of extinguishment for aconsiderably longer period of time whereby the large volume flow willextinguish any flame and the reduced volume flow over a longer period oftime will cool the area below the rekindling point.

5. A method for controlling grease fires in a vat having a chimneyvented hood thereover comprising the steps of initially directing a highpressure, high volume, difiused stream of extinguishment generallyhorizontally over and across the surface of the vat, flooding said highpressure, high volume, extinguishment into the open area of the hood,and directing said high pressure, high volume, extinguishment in thechimney, all for extinguishing any flame therein, automatically reducingthe pressure and the volume of the extinguishment from the same sourceof extinguishment and directing the same over and across said vat, intosaid area in the hood and into the chimney, said lower pressure, lowervolume stream of extinguishment serving to cool the grease andsurrounding surfaces to below the rekindling point thereof so as toprevent rekindling of said grease fire.

6. The fire control method of claim 5 wherein the duration of said highpressure, high volume, stream ofextinguishment is relatively short whencompared with the longer duration, lower pressure, lower volume flow ofextinguishment.

'7. A method for controlling fires in a control zone using fire controlequipment having a source of pressurized extinguishment, a valveassembly operatively connected to said source of extinguishment andhaving an outlet port, means connecting said outlet port with a nozzledirected toward said control zone, and means associated with saidcontrol zone for detecting the presence of flame or excessive heat, saidmethod comprising the steps of detecting flame or excessive heat, saidmethod comprising the steps of detecting flame or excessive heat by saidlast named means, valve means in said valve assembly activated by saiddetecting means for releasing the pressurized extinguishment, thepressure of said extinguishment opening said valve means for high volumeflow of extinguishment to said nozzle and from the nozzle over saidcontrol zone, reduction of pressure of extinguishment in said sourcepermits the valve means to reduce the volume of flow to a lower level,flowing said lower volume flow of extinguishment over the control zonefor a period of time considerably longer than the high volume flow.

1. A method for controlling fires, comprising the steps of rupturing afrangible element by exposure to excessive heat, releasing a highpressure and high volume flow of extinguishant from a storage containerinto a system of fire control piping, directing the high pressure andhigh volume flow of extinguishment over the burning area, automaticallyreducing the pressure and volume of flow of extinguishment from the samesource of extinguishment and over the same area, whereby the largevolume flow will extinguish any flame and the reduced flow will cool thearea below the rekindling point.
 2. The method for controlling fires asclaimed in claim 1 and wherein the high volume and high pressure flow ofExtinguishment is maintained for a relatively short period of time andthe reduced volume flow is maintained for a comparatively long period oftime.
 3. The method for controlling fires as claimed in claim 1 whereinthe ratio of the duration of the reduced volume flow to the large volumeflow is of the order of 18 to
 1. 4. A method for controlling greasefires, comprising the steps of initially directing a large volume flowof extinguishment over the burning area, continuing said large volumestream of extinguishment for a short period of time, automaticallyreducing the volume of the flow of extinguishment from the same sourceof extinguishment and over the same area, continuing the reduced volumeof flow of extinguishment for a considerably longer period of timewhereby the large volume flow will extinguish any flame and the reducedvolume flow over a longer period of time will cool the area below therekindling point.
 5. A method for controlling grease fires in a vathaving a chimney vented hood thereover comprising the steps of initiallydirecting a high pressure, high volume, diffused stream ofextinguishment generally horizontally over and across the surface of thevat, flooding said high pressure, high volume, extinguishment into theopen area of the hood, and directing said high pressure, high volume,extinguishment in the chimney, all for extinguishing any flame therein,automatically reducing the pressure and the volume of the extinguishmentfrom the same source of extinguishment and directing the same over andacross said vat, into said area in the hood and into the chimney, saidlower pressure, lower volume stream of extinguishment serving to coolthe grease and surrounding surfaces to below the rekindling pointthereof so as to prevent rekindling of said grease fire.
 6. The firecontrol method of claim 5 wherein the duration of said high pressure,high volume, stream of extinguishment is relatively short when comparedwith the longer duration, lower pressure, lower volume flow ofextinguishment.
 7. A method for controlling fires in a control zoneusing fire control equipment having a source of pressurizedextinguishment, a valve assembly operatively connected to said source ofextinguishment and having an outlet port, means connecting said outletport with a nozzle directed toward said control zone, and meansassociated with said control zone for detecting the presence of flame orexcessive heat, said method comprising the steps of detecting flame orexcessive heat, said method comprising the steps of detecting flame orexcessive heat by said last named means, valve means in said valveassembly activated by said detecting means for releasing the pressurizedextinguishment, the pressure of said extinguishment opening said valvemeans for high volume flow of extinguishment to said nozzle and from thenozzle over said control zone, reduction of pressure of extinguishmentin said source permits the valve means to reduce the volume of flow to alower level, flowing said lower volume flow of extinguishment over thecontrol zone for a period of time considerably longer than the highvolume flow.